Second-order conditional modeling of turbulent nonpremixed flames with a composite pdf

Journal Article · Wed Jul 01 04:00:00 EDT 1987 · Combust. Flame; (United States)

DOI:https://doi.org/10.1016/0010-2180(87)90018-6· OSTI ID:5888355

Chen, J Y

A second-order conditional model for turbulent nonpremixed flames with a composite probability density function (pdf) is presented. The composite pdf represents three parts of the scalar field: a fully turbulent part, a surrounding nonturbulent part, and a superlayer part. The conditional equations are derived using Favre averaging (density weighting) with the interfacial interaction terms appearing in explicitly separate groups. These equations are closed by a second-order scheme and models for the interfacial terms. Nitric oxide formation is computed by a model including the effects of intermittency and nonequilibrium oxygen-atom concentration. The performance of the proposed model is evaluated by comparisons of model predictions with three different sets of experimental data for turbulent nonreacting and reacting jets. The calculated results are also compared with those obtained without the consideration of the superlayer and with those predicted by an unconditional model using different pdf shapes. Although the uncertainties of the experimental data prevent us from drawing solid conclusions from these comparisons, it is shown that the model predictions can be improved by incorporating intermittency and a composite pdf. The improvements are most significant for the scalar field. The nitric oxide calculations indicate that the effect of the superlayer can be significant, suggesting the use of the proposed model in this area.

• Research Organization: Combustion Research Facility, Sandia National Labs., Livermore, CA 94550
• OSTI ID: 5888355
• Journal Information: Combust. Flame; (United States), Journal Name: Combust. Flame; (United States) Vol. 69:1; ISSN CBFMA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
400800* -- Combustion
Pyrolysis
& High-Temperature Chemistry
99 GENERAL AND MISCELLANEOUS
990220 -- Computers
Computerized Models
& Computer Programs-- (1987-1989)
CHALCOGENIDES
CHEMICAL REACTION YIELD
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
DENSITY
FLAME PROPAGATION
FLAMES
FUNCTIONS
INTERACTIONS
INTERFACES
JETS
MIXING
NITRIC OXIDE
NITROGEN COMPOUNDS
NITROGEN OXIDES
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PROBABILITY
SCALAR FIELDS
SIMULATION
TURBULENCE
WEIGHTING FUNCTIONS
YIELDS